BIO 3547 Lecture Notes - Haliotis Rufescens, Chemoreceptor, Opportunity Cost

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8 Feb 2013

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old animals made decisions thru life as it matured (settle, eat, associate)
all decisions made in environment that varies in space and time
habitat: environment in which an organism lives; seeks food, rest, nest sites, escape routes
in habitat
suitable habitats: good predictors of conditions suitable for future survival+reproduction
chemosensory cue of red abalone larvae settles on surface that has potential of supplying
food for future survival and reproductive success
visual info provides useful cues; presence of already settled individuals is indication
flycatchers assess quality of habitat by seeing how well neighbours are doing; (settle in
areas where broods (abundant food) artificially enlarged)
some highly social animals vote on quality of habitats (worker bees dance to communicate
location, site that excites most workers is chosen)
animals compete for high-quality habitats; may improve its fitness by establishing
exclusive use of habitat
may do this by establishing territory which excludes conspecifics (same species) by
advertising it owns area and chasing others away (but advertising and chasing takes energy)
cost-benefit approach: assumes an animal has only a limited amt of time and energy to
devote to activities; [costs must not outweigh benefits]; ecologists can make predictions, design
experiments, and make observations explaining why patterns evolve the way they do
benefits of behaviour are improvements in survival and reproductive success; 3 costs
energetic cost: difference btwn energy at rest and energy used to perform behaviour
risk cost: increased change of getting killed/injured when performing behaviour
opportunity cost: sum of benefits the animal forfeits by not performing other behaviours
Moore and Marler: male lizards with more testosterone spent more time patrolling
territories, doing advertising displays, used 1/3 more energy than control males. They had less time
to feed, got fewer insects, stored less energy, died at higher rate
some animals defend all-purpose territories that include all resources (tigers, songbirds)
food supplies cannot be defended if widely distributed or fluctuate a lot (ex oceans)
some animals defend territory used only for mating (male grouse congregate on display
grounds, defending small area. Males often use so much energy that less tired males eventually
evict them)
foraging theory: helps us understand survival (ultimate) value of feeding choices; benefits
= nutritional value, and costs similar to those for territorial defense
more rapidly an animal captures food, more time+energy it will have for other things
characterize each type of available food item in 2 ways: time it takes animal to pursue,
capture, and consume item; and by amt of energy an item contains
most valuable food type is one that yields most energy per unit of time expended
ocan determine rate at which an animal would obtain energy given foraging strategy
oanimal gains most energy by taking only most valuable type and ignoring all others;
but as that type depletes, it adds less valuable types (ex fish would ignore small water fleas if there
are large ones)
for bluegills, only energy content of water fleas mattered; some animals travel great
distances for nutrients
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